The rubber sheet for turntable is used to isolate a disc record from acoustic outputs from a loudspeaker, vibrations of a record player itself, etc., thereby preventing the occurrence of howling and the deterioration of SN ratio due to vibrations of the disc record itself during its reproduction. The howling is a sort of oscillation phenomena due to the feedback of acoustic outputs from a loudspeaker to a pickup and occurs due to the transmission of vibrations from the speaker to the record player via the floor or rack where the record player is mounted, or due to the direct vibrations of the record player cabinet caused by a sound pressure from the loudspeaker. It is needless to say that any normal playback of the disc record cannot be effected when the howling occurs. Even where no howling takes place, the frequency response of the pickup output would be altered and local resonance and the like would be caused by such external vibrations, and the tone quality of reproduced sounds would be affected adversely by the increase of inter-modulation distortion, the deterioration of transient phenomena, etc. The howling takes place mostly due to external vibrations from the floor or rack where the record player is mounted. The majority of such external vibrations is of the order not more than 100 Hz and particularly includes a superlow frequency component of approximately 5 to 10 Hz. To provide for an effective inhibition of howling, a rubber sheet for turntable which exhibits excellent vibration-absorbing properties in such superlow frequency region is desirable.
However, conventional rubber sheets for turntable which are made of natural rubber, isoprene rubber, chloroprene rubber, butyl rubber, styrene-butadiene rubber, butadiene rubber, silicone rubber or urethane rubber, or mixtures thereof are inferior in vibration-absorbing properties, especially in the superlow frequency range, and are unable to protect effectively the tone quality of reproduced sounds from deteriorating due to howling or external vibrations.